Backstory: Iraq legal advice

Shortly before the start of the Iraq war, the then-attorney general Lord Goldsmith published a nine-paragraph statement saying why he thought the invasion would be legal under international law.

It was published as a written answer in the House of Lords and it said that the United Nations security council resolution 1441, passed in the autumn of 2002, "revived" the authority to go to war explicitly contained in an earlier security council resolution.

Advice from government law officers is normally kept secret. But Tony Blair had failed to secure another UN security council resolution explicitly authorising the invasion – the so-called "second resolution" – and at the time he was under intense pressure to prove to the public that war would be lawful.

Many MPs assumed that the nine-paragraph statement was a summary of a more considered legal opinion drawn up by Goldsmith in private.

But after the war it emerged that the nine-paragraph document – published on March 17 2003 – was all the legal protection the government had.

More embarrassingly, it also transpired that Goldsmith had written a much more considered, 13-page legal opinion on March 7 that expressed considerable reservations about the legality of the invasion.

The March 7 document was never shown to the cabinet, which met on March 13 and again on March 17 to discuss Iraq. Some campaigners believe that ministers were not told the full truth about the legal question marks raised by Goldsmith and that, if the government has to publish the minutes of those two cabinet meetings, they will prove that ministers were misled.

Goldsmith has also been criticised for allegedly changing his mind between March 7 and March 17. He has argued that what he said on March 17 was consistent with what he wrote on March 7, but his critics have claimed that he amended his stance in response to political pressure.

To make matters more complicated, there have even been allegations that Goldsmith changed his mind not once, but twice.

When Elizabeth Wilmshurst, the deputy legal adviser to the Foreign Office, resigned in March 2003 because she thought the invasion would be illegal, she wrote a letter suggesting that Goldsmith had originally supported the internal Foreign Office position that war would be unlawful without a second resolution.

Goldsmith's reservations – March 7

In his March 7 document, addressed to the prime minister and marked "secret", Goldsmith said: "I remain of the opinion that the safest legal course would be to secure the adoption of a further resolution to authorise the use of force.

"Nevertheless, having regard to the information on the negotiating history which I have been given and to the arguments of the US administration which I heard in Washington, I accept that a reasonable case can be made that the resolution 1441 is capable in principle or reviving the authorisation in 678 [the earlier resolution] without a further resolution.

"However, the argument that resolution 1441 alone has revived the authorisation to use force in resolution 678 will only be sustainable if there are strong factual grounds for concluding that Iraq has failed to take the final opportunity. In other words, we would need to be able to demonstrate hard evidence of non-compliance and non-cooperation."

Goldsmith also told Blair: "A 'reasonable case' does not mean that if the matter ever came before a court I would be confident that the court would agree with this view."

He also warned the prime minister that opponents of military action might try to bring a case against members of the government, either under international law or domestic law.

"Given the strength of opposition to military action against Iraq, it would not be surprising if some attempts were made to get a case of some sort off the ground. We cannot be certain that they would not succeed," he said.

Sign up for the Guardian Today

Our editors' picks for the day's top news and commentary delivered to your inbox each morning.